From BlenderWiki
Children are Hair and Keyed particles assigned subparticles. They make it possible to work primarily with a relatively low amount of Parent particles, for whom the physics are calculated. The children are then aligned to their parents. Without recalculating the physics the number and visualization of the children can be changed.
- Children can be emitted from particles or from faces (with some different options). Emission from Faces has some advantages, especially the distribution is more even on each face (which makes it better suitable for fur and the like). However, children from particles follow their parents better, e.g. if you have a softbody animation and don’t want the hair to penetrate the emitting mesh. But see also our manual page about Hair.
- If you turn on children the parents are no longer rendered (which makes sense because the shape of the children may be quite different from that of their parents). If you want to see the parents additionally turn on the Parents button in the Visualization panel.
- Children carry the same material as their parents and are colored according to the exact place from where they are emitted (so all children may have different color or other attributes).
The possible options depend from the type of particle system, and if you work with Children from faces or Children from particles. We don’t show every possible combination, only the settings for a Hair particle system.
Particles
- Amount: The number of children in the 3D window.
- Render Amount: The number of children to be rendered (up to 10.000).
- Rad: The radius in which the children are distributed around their parents. This is 3D, so children may be emitted higher or lower than their parents.
- Round: The roundness of the children around their parents. Either in a sphere (1.0) or in-plane (0.0).
- Clump: Clumping. The children may meet at their tip (1.0) or start together at their root (-1.0).
- Shape: Form of Clumping. Either inverse parabolic (0.99) or exponentially (-0.99).
- Size/Rand: Only for Emitter and Reactor systems. A multiplier for child particle size in relation to the size of their parents, and a random variation.
- Rough1/Size1: It is based on children location so it varies the paths in a similar way when the children are near.
- Rough2/Size2/Thresh: It is based on a random vector so it’s not the same for nearby children. The threshold can be specified to apply this to only a part of children. This is useful for creating a few stray children that won’t do what others do.
- RoughE/Shape: “Rough End” randomizes path ends (a bit like random negative clumping). Shape may be varied from <1 (parabolic) to 10.0 (hyperbolic).
Kink/Branch
With Kink you can rotate the children around the parent, Branch branches the hair (dependent on the number of children). These settings don’t work alternatively with roughness, but additionally (it seems there would have been another panel necessary for all the options).
- See above picture (Image 3) for the different types of Kink.
- X/Y/Z: Axis for the offset of the children.
- Freq: The frequency of the offset (1/total length). The higher the frequency the more rotations are done.
- Shape: Where the rotation starts (offset of rotation).
- Amplitude: The amplitude of the offset.
For branching the parameter Threshold is especially important. 0.0 branches at the very tip of the particles (i.e. no branching at all), 1.0 branches at the root of the particles.
- Animated: Branches in every frame of an animation in a new, random way.
- Symmetric: Start- and end-points are the same.
Faces
Children may also be emitted between the Parent particles on the faces of a mesh. They interpolate between adjacent parents.
- This is especially useful for fur, because you can achieve an even distribution.
- Some of the children can become virtual parents, which are influencing other particles nearby.
- Children from faces can have Child simplification.
Many options are the same as for Children from particles, but you don’t have roundness and branching. There are two additional settings:
- Spread: Spread children from the faces.
- Use Seams: Use seams to determine parents. This makes it easier to create sharp partings.
